<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    class Utils {
      query() {
        // ....
      }
    }
    class Dialog extends Utils {
      constructor() {
        super()
        // new Utils.query()
        // this.query()
      }
    }
  </script>
</body>
</html>